Rfid transducer alignment system

ABSTRACT

A radio frequency identification (RFID) system having the capacity to detect conditions of alignment, wherein the system may be used with hand-held, fixed-in-place, stationary, and permanently mounted apparatus. The system includes an RF interrogator configured for use with dental x-ray, medical imaging, film, and digital radiography apparatus, and may include a multiplicity of RF transponders or interrogators. An RF interrogator, an RF transponder, and an x-ray sensitive imaging device, and its holder are configured to be critically aligned to a dental x-ray machine head apparatus, rendering repeat imaging unnecessary. The x-ray emitter may be further configured to automatically obtain a desired x-ray image or configured so that the device cannot activate and provide a radiograph until alignment with the transponder and associated x-ray sensitive imaging device has occurred.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/959,249, filed Dec. 18, 2007; which is a continuation of U.S. patentapplication Ser. No. 11/205,348, filed Aug. 16, 2005, issued as U.S.Pat. No. 7,319,396. This application also claims the benefit of U.S.Provisional Application Ser. No. 60/602,223, filed Aug. 16, 2004 andU.S. Provisional Application Ser. No. 60/602,751, filed Aug. 18, 2004,the contents of which are hereby incorporated herein by reference.

BACKGROUND

1. Technical Field

This disclosure relates generally to providing enhanced functionalityfor common radio frequency identification (RFID) technologies anddevices, and more specifically to the detection of radio frequency (RF)component alignment, for example, an x-ray critical-alignment apparatus.

2. Description of the Related Art

The general function of a given RFID transponder or “tag” is to act as a“remote sensor device” for a given RF interrogator. When enabled, an RFinterrogator's carrier transmit/data receive coil produces anelectromagnetic field of flux at a predetermined frequency, whichcreates a radiated “carrier” transmit signal. When such an RFID tag isplaced in close proximity to an RF interrogator, the RFID tag “powersup.” Accordingly, the activated RFID tag is impressed with the carriertransmit signal, and in response certain passive electronic componentsof the RFID tag begin to self-oscillate, which creates a secondaryelectromagnetic (EM) field of flux at a predetermined frequency withinand about the RFID tag. After the RFID tag is activated and when thereceived carrier transmit signal is of predetermined ideal amplitude, asset by predefined design criteria of the RFID tag and firmware thereof,the RFID tag begins to transmit a serial data stream of “canned/stored”information. Data transmission is generally accomplished by means of theRFID tag shunting its carrier-receive/data transmit coil or antenna,according to the RFID tag's design and predefined data protocol, etc.

When an RFID tag begins to oscillate so as to radiate a specific RFsignal and electromagnetic field of flux, the RF interrogatorcarrier-transmit coil becomes impressed with the RFID tag's “return” RFsignal. The impressed return RF signal upon the RF interrogatorcarrier-transmit coil is commonly referred to as “backscatter” or abackscatter signal. The backscatter signal generally alters certaincharacteristics of the RF interrogator carrier-transmit signal. Suchcarrier-transmit signal alterations, even as they might be minuteinitially, can be detected by appropriate RF interrogator front-endcircuitry. When actual RFID tag serial data stream transmission occurs,the RF interrogator acts to detect the backscatter signal, generallythrough the use of an “envelope detector” circuit. The RF interrogatorwill then condition/filter and amplify the backscatter signal to obtaina resultant “clean” data stream signal. Thereafter, the RFinterrogator's microcontroller may “test/decode/read” and be configuredto respond to the resultant signal, for example, by inputting a productname, code, and price into a cash register when an item containing anRFID tag is scanned, or by setting off an alarm when someone walks outof a store without purchasing an item containing an RFID tag. However,current RFID technology has been limited to its namesake: product“identification.” Thus, the technology has not been applied inalternatively new ways or with regard to differing applications.Accordingly, RFID technology has not been applied to sensor “alignment”functionality, such as for an indication of best alignment ofnon-contact x-ray film positioning.

During the common and standard process of taking dental x-rays, specialtools and several tedious steps are often required. Two options fortaking x-rays are known wherein: 1) a molded x-ray film holder, whichgenerally has sharp edges around its periphery, is loaded with an x-rayfilm and together is placed in a patient's mouth to bite down on (whichis most discomforting for most patients due to the sharp edges), suchthat a dental technician or doctor must then visually estimate theposition of the film holder so as to take an x-ray; or, 2) wherein amolded x-ray film holder, also having sharp edges around its periphery,is loaded with an x-ray film and together is placed onto a “rim holder”device (a long bar, generally of metal, with an x-ray film holderreceiving device at one end, and an x-ray head apparatus receivingdevice at the other end), which is then collectively placed in apatient's mouth to bite down on (which is extremely discomforting formost patients due to the sharp edges, as well as due to the bulkiness ofthe rim holder apparatus) with only the x-ray head apparatus receivingdevice protruding from the patient's mouth such that a dental technicianor dentist would then place the x-ray head into the x-ray receivingdevice so as to take an x-ray radiograph.

Aside of the general need for special alignment tools, the disadvantagesof the above two options are several: 1) often additional x-rays arerequired to be taken because of improper alignment of the x-ray headapparatus to the x-ray film, especially when the location/position ofthe x-ray film is manually estimated, and often, when; 2) the rim holderis improperly located/positioned in a given patient's mouth, whichcreates; 3) loss of both time and expense, and, which additionally; 4)exacerbates a given patient's discomfort. The present disclosure wasdevised to overcome these challenges. The first concept considered wasto provide a system that might permanently eliminate the need for a rimholder device/alignment tool. The second concept considered was to alterthe design of the common x-ray film holder device so as to eliminate itssharp edges. The third concept was to identify a system by which thetaking of dental x-rays would become less intrusive, yet more accurate.

The basis for RFID technology appears to offer the most ideal solutionto the current problems with dental x-rays. Heretofore, RFID technologyin practice and application has mostly been used for product and othercommodity “identification” purposes. Apparently, such technology had notbeen used for exacting a critical alignment of an x-ray head apparatusto an (often hidden) x-ray film. One aspect unknown in the art was asystem that would permit attachment of a predetermined RF tag inproximity of an apparatus and that would incorporate those componentsrequired for building a customary RF tag device. Such a system waslacking in newer technology apparatus (for example, digital radiography)and in well-known technology apparatus, such as dental x-ray film holderdevices. Thus, a new RF tag architecture and device is required.However, digital radiography, in terms of equipment and supplies, isextremely expensive, and as it relates to practicing dentists remains ofprice and expense that is currently highly prohibitive to manifolddentists. Therefore, a great many dentists, especially in rural-typeenvironments, still make use of the established technology such that thedentists are still using both x-ray film and x-ray film holder devices.

Another aspect unknown in the art is an electronics design that wouldact as an RF interrogator and that would have a remote yet attached“transmit/tag sense/antenna” coil. Such a coil, which transmits acarrier frequency to enable the new RF tag device and that also acts toreceive data from the enabled new RF tag device, would need to bedevised so as to fit upon or mechanically interface to the active end ofa given dental x-ray head apparatus.

One issue in creating a dental-oriented non-contact RF transducer systemis that a given dental RF tag must be physically smaller than theaccompanying dental RF carrier transmit/data receive coil. In fact, tomeet the criteria for obtaining a “best-alignment” scenario with regardto most RF-based transducer alignment systems, a given RF tag thereof,and particularly its RF carrier receive/data transmit coil, mustgenerally remain smaller than the system's associative RF carriertransmit/data receive coil. Another issue to operational practicalityfor a dental application is that “non-contact” operation be obtained,wherein a given x-ray head apparatus would never (intentionally or needto be caused to) touch a patient's face, especially in the course ofalignment of the x-ray head apparatus to the dental RF tag within apatient's mouth. This issue is not in the least trivial since known RFIDtechnology did not allow for spacious RF sensor/tag distance sensing,particularly in wholly scaled-down RFID systems. Various common RF tagscurrently available were used in test beds, and were found to be grosslylacking as it concerned desired operational distance to a similarlyavailable RF interrogator.

It was found that when an RF tag was placed in a patient's mouth andbehind the teeth (as would normally occur in a dentist's office), thenvalid sensing-distance was no more than one inch, and often much less.The RF interrogators carrier transmit/data receive coil needed to beplaced inward on, at or extremely close to the cheek in order to “read”a common RF tag. Thus, commonly available systems were both non-idealand impractical for a dental x-ray application. Therefore, there is aneed for an enhanced RF interrogator analog “front-end” circuit havingadditional features.

As will be appreciated by those of skill in the art, providing a dentalx-ray RFID positioning system incurs several design challenges,including: 1) dental RF tag size, which being rather small, producesonly a small RF field of flux at resonance; 2) sensing distance to agiven RF tag of at least two inches is desirable; 3) dental RFinterrogator carrier transmit/data receive coil size, which also beingrather small, has a limited range for detecting a remotely radiated RFsignal from an RF tag when an RF tag is activated; 4) data streamsignals received by the dental RF interrogator carrier transmit/datareceive coil are in the microvolt range when the RF tag is severalinches away; 5) such signals, when then fed into operational amplifiercircuits, generally can not be distinguished or easily separated frombase-noise levels of operational amplifier circuits, and thus, 6) theresultant signal from the operational amplifier circuits contains bothinherent and free-air radiated noise, as well as the desired datasignals RF carrier transmission components, making “valid” signaldetection difficult; and 7) even with filtering, free-air radiatedalternating current (A.C.) signals are amplified and become part of thenet/final signal structure from the operational amplifier circuits,thereby, grossly affecting the final signal integrity, particularly whenobtained by a highly sensitive RF interrogator analog front-end circuit.

Thus, what is needed and heretofore unknown is an RF transducernon-contact alignment system that fulfills dental x-ray applicationrequirements, that solves these identified technical challenges, andthat provides a fully operational product. There is also a need forRFID-type technology operable over greater distances between certaintypes of RF tags and interrogators. There is also a need to fill thetechnological gaps and voids in the practical applications of RFIDtechnology. There is a further need for critical RF tag/sensor alignmentfunctionality to establish new applications within the RFID industry,especially for critical RF tag alignment.

BRIEF SUMMARY

The present disclosure is directed to a new application for RFIDtechnology that will enhance the industry as a whole. The RFID system ofthe present disclosure utilizes certain design methodologies so as toprovide inexpensive and uncomplicated apparatus for detecting RFIDtag-to-RFID interrogator alignment.

The present disclosure provides a simple, functionally enhanced, and newRFID system concept, wherein presently available RFID systems have anopportunity to be improved upon or expanded by various new features andfunctionalities, including the capacity to detect the parameter of“alignment.” The present disclosure further provides a new type of RFinterrogator specifically designed for the dental industry, medicalimaging systems, and other such industries for use with digitalradiography. The present disclosure also provides a new RFID systemhaving a new type of RF tag device and x-ray film holder. The RF tagdevice and x-ray film holder may allow presently utilized dental x-rayfilms to be placed into a re-devised, intelligent, and more comfortable(for the patient) film holder. The RF tag device and x-ray film holdermay be applied to contemporary “digital x-ray imaging sensors” byallowing contemporary digital x-ray imaging sensors to be criticallyaligned to a given dental x-ray machine head/gun apparatus, renderingrepeat imaging unnecessary.

The present disclosure also provides a new RFID system, wherein dentalx-rays may be taken with great accuracy resulting from the ability todenote critical alignment of a digital x-ray imaging sensor and/ordental x-ray film in a patient's mouth. The system of the presentdisclosure may be configured to denote critical alignment of a digitalx-ray imaging sensor or dental x-ray film holder within a patient'smouth without the need for commonly used special tools, procedures ordevices. The RFID system may be configured to store patient and otherinformation in the RF tag device or x-ray film holder or both.

The present disclosure includes a new RFID system utilizing x-rays andother radiography imaging so as to provide an automatic RF tag seekingmode of operation. For example, a given x-ray head apparatus may beconfigured to move on its own accord. When enabled, the x-ray headapparatus may locate a (perhaps) hidden RF tag device, such as during adental application, and ultimately align itself to a given located RFtag device. The x-ray head apparatus may be further configured toautomatically obtain a desired x-ray image and store certain data. Thex-ray head apparatus may be further configured so that the device cannotactivate and provide a radiograph until alignment to a given RF tagdevice has occurred. Such a system provides a new safety mechanismagainst impromptu enabling of the x-ray machine apparatus and may renderrepeat imaging unnecessary.

The present disclosure improves upon the present designs of certain RFIDinterrogator devices by providing for one or a multiplicity of RFinterrogator carrier transmit/data receive coils, depending on theapplication or the need. One or a multiplicity of RF interrogatorcarrier transmit/data receive coils may be provided in a given system,depending on the application or the need, each resonant to the same ordiffering frequencies. In a multiple coil system, and depending on theapplication, the size of the RF interrogator carrier transmit/datareceive coils may vary. Further, the multiplicity of RF interrogatorcarrier transmit/data receive coils may be fixed about a given RFinterrogator enclosure, or placed remote from the RF interrogator byusing one or more appropriate cable devices.

The present disclosure provides for improving upon the present designsof certain RFID interrogator devices for use with hand-heldfixed-in-place, stationary and permanently mounted applications. Suchhand-held, fixed-in-place and similar applications may be independent ofan applied power source, for example, an alternating current (A.C.) wallsocket or a direct current (D.C.) battery.

The present disclosure improves upon the present designs of certain RFIDinterrogator devices by providing a system for indication of thedetection and presence of a given RF tag by a given RF interrogator byvarious devices and circuits, including either or both: audio or visualtechniques and apparatus. The system provides for indication, withinpredefined limits, of the distance from a given RF interrogator'scarrier transmit/data receive coil to a given detected RF tag by variousdevices and circuits, including either or both audio or visualtechniques and apparatus. The system also provides for indication of thedetection of valid data from a given detected RF tag by a given RFinterrogator by various devices and circuits, including either or bothaudio or visual techniques and apparatus.

The present disclosure improves upon the present designs of certain RFIDdevices by providing a system for indication of critical alignment of agiven detected RF tag by a given RF interrogator by various devices andcircuits, including either or both audio or visual techniques andapparatus. The system may provide indication of a given RFinterrogator's status, such as “elapsed warm-up time,” or “ready foroperation,” for example, from various devices and circuits such as fromaudio or visual techniques and apparatus. The system may also providefor indication of a given RF interrogator's carrier transmit frequencyor frequencies from such devices, circuits, and techniques. The systemmay also provide for varying and indication of a given RF interrogator'scarrier transmit frequency or frequencies. Further, the system providesfor tuning/detuning and indication of a given RF interrogator's carriertransmit frequency or frequencies by various devices and circuits,including either or both audio or visual techniques and/or apparatus.

The present disclosure improves upon the current designs of certain RFIDinterrogator devices by providing a system for selection and indicationof a given RF interrogator's explicit carrier transmit drive signalwaveform or waveforms by various devices and circuits, including eitheror both audio and visual techniques and apparatus. The system may alsoprovide for indication of a given RF interrogator's carrier transmitamplitude or amplitudes by such devices, circuits, and techniques. Thesystem may further provide for indication of the presence of a given RFinterrogator's carrier transmit signal or signals from such devices,circuits, and techniques. The system also may provide for indication ofthe presence of a given RF interrogator's carrier transmit/data receivecoil or coils. Further, the system may provide for selection, as well asthe indication of selection, of one or more carrier transmit/datareceive coils attached to a given RF interrogator. Also, the system mayprovide for the indication of the current mode of operation of a givenRF interrogator (such as idle or seek mode) by various devices andcircuits, including either or both audio or visual techniques andapparatus.

The present disclosure improves upon the current designs of certain RFIDinterrogator devices by providing a system for on-the-fly or in-situ RFtag programming and the indication of the same by various devices andcircuits, including either or both audio or visual techniques andapparatus. The system may provide for sensing the parameter of criticalalignment in a fixed or variable three-dimensional space and indicationof the same by such devices, circuits, and techniques. The system mayfurther provide for audio feedback for a user in the course ofoperation, whether in the form of tones or voice by various devices andcircuits. Further, the system may provide for audio feedback for a userin the course of operation, whether in the form of tones or voice,wherein pitch and/or volume, or expression, or such that, might bealtered by a given RF interrogator's response to certain sensedparameters, input, or by such various devices and circuits.

The present disclosure improves upon the current designs of certain RFIDinterrogator devices by providing a system having a user keyboard ofsome nature, whereby a user may, for example, input or set or definecertain data or criteria, or retrieve information and other data from orto various devices and circuits. The system may also be configured withone or more display apparatus, primarily for user feedback, whether itor they be LED or LCD, or the like, in nature or a mixture thereof. Thesystem may provide for at least one external communications port. Suchan external communications port may accommodate a transmission or datalink to and with a computer or a printer or both. Further, the systemmay provide for remote placement of certain visual indicators or audiodevices near or at a given RF interrogator carrier transmit/data receivecoil or upon an RF interrogator.

The present disclosure improves upon the present designs andfunctionality of RFID interrogator devices and systems and theircomponents by providing not only for RF tag or sensor detection andreading, and sorting, or other functions as pertinent to a givenapplication, but for explicitly programming a given RF tag or sensordevice by various devices and circuits.

The present disclosure includes a method for constructing an RF tagenvelope from a rubber, plastic, vinyl, or other suitable material so asto allow for dental x-ray film insertion or digital x-ray imaging sensorattachment. The RF tag envelope containing an electronics circuit mayalso be constructed from such materials so as to allow for dental x-rayfilm insertion or digital x-ray imaging sensor attachment. Such an RFtag envelope may be fabricated so as to allow for dental x-ray filminsertion or digital x-ray imaging sensor attachment that the electroniccircuit may be minimally comprised of a coil apparatus, a capacitordevice, a power conditioning circuit and a microcontroller circuitdevice.

The present disclosure further includes a method for constructing andfabricating an RF interrogator envelope from rubber, plastic, vinyl,metal, or other suitable material. The RF interrogator envelope mayinclude a printed circuit board apparatus and whereon various and sundryelectronic components may be attached. The electronic components on thecircuit boarding include certain discrete analog and digital electronicdevices, passive electronic devices, a microcontroller circuit deviceand visual display and audio devices. The circuit board may also includeor have attached one or more connectors, including that of an appliedpower source connector.

The present disclosure also includes a method for constructing andfabricating an RF envelope from plastic, vinyl, or other suitablematerial for use with a dental x-ray machine head or gun apparatusattachment, such as insertion. The RF antenna envelope may be fabricatedso that a dental x-ray machine head or gun apparatus is attached orinserted on one end, and a coil apparatus may be attached to theopposite end of the envelope. Such an RF antenna envelope may beconfigured so that visual or audio indicator devices and one or moreconnector devices may be attached to the envelope. Such connectordevices may attach to one or more cable apparatus so that the RF antennaenvelope may ultimately be attached to the RF interrogator envelope.

The present disclosure includes a method for constructing andfabricating an RF tag envelope from plastic, vinyl or other suitablematerial. The RF tag envelope may be configured with various and sundryelectronic components having discrete analog and digital electronicdevices, passive electronic devices or microcontroller circuit devicesso as to construct an RF tag device. Such an RF tag device may beconfigured for attachment about a digital radiography apparatus or insynchronicity with customary x-ray imaging apparatus, for example, x-rayfilm requiring an x-ray film holder.

The present disclosure further includes a method for utilizing an RF tagdevice, RF antenna device, and an RF interrogator device, each in acompletely assembled form, wherein each component is configured to workin synchronicity with each other component. The components may befurther configured together and collectively to form and operate as anRFID transducer apparatus and system. Such an RFID transducer apparatusand system may function and be used as a non-contact “alignment”apparatus or tool. In certain applications the RFID transducer apparatusand system may perform more basically as an enhanced RFID system.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Other features and advantages of the disclosure will become apparentfrom the following detailed description, taken in conjunction with theaccompanying drawings, which illustrate, by way of example, the featuresof the disclosure.

FIG. 1 depicts a system diagram of an embodiment of an RFID transduceralignment system generally devised for dental applications according tothe present disclosure.

FIGS. 2 a and 2 b depict a subsystem block diagram of an embodiment ofan RF interrogator according to the present disclosure.

FIG. 3 depicts a subsystem block diagram of an embodiment of an RFantenna according to the present disclosure.

FIG. 4 depicts a subsystem block diagram of an embodiment of an RF tagaccording to the present disclosure.

FIG. 5 depicts a portion of a schematic diagram of an embodiment of theRFID transducer alignment system according to the present disclosure.

FIG. 6 depicts a portion of a schematic diagram of an embodiment of theRFID transducer alignment system according to the present disclosure.

FIG. 7 depicts a portion of a schematic diagram of an embodiment of theRFID transducer alignment system according to the present disclosure.

FIG. 8 is a schematic representation of an alternate embodiment of an RFtransducer alignment system of the present disclosure illustrating anexample of a hand-held apparatus having both an RF interrogator and anRF antenna.

FIG. 9 is a schematic representation of an alternate embodiment of an RFtransducer alignment system of the present disclosure illustrating amulti-axis alignment system having three RF antennas and three RF tagsin an “x”, “y”, and “z” orientation.

FIG. 10 is a schematic representation of an alternate embodiment of anRF transducer alignment system of the present disclosure illustrating adental digital x-ray imaging sensor and an RF tag device.

FIG. 11 is a schematic representation of an alternate embodiment of anRF transducer alignment system of the present disclosure illustrating amulti-form RF antenna.

FIGS. 12A and 12B are schematic representations of an alternateembodiment of an RF transducer alignment system of the presentdisclosure illustrating a multi-point RF tag detection and alignmentfeedback system for a winged aircraft.

FIG. 13 is a schematic representation of the RFID alignment system ofthe present disclosure applied to a dental x-ray apparatus.

DETAILED DESCRIPTION

As shown in the drawings for purposes of illustration, the presentdisclosure is directed to a beneficial and novel electronic design, thebasis of which is founded on RFID (radio frequency identification)technology. The present disclosure provides an altogether new RFIDapplication having enhanced levels of utility and practicalfunctionality over present-day common or standard uses of the RFIDtechnology. This RFID system is beneficially applicable to thoseapparatus or products that require or might make use of non-contactpower control or operation, non-contact accessibility or enabling, andnon-contact entry. The disclosure is also useful for those products,apparatus, or devices that require or might make use of non-contactobject or target sensing or detection, intelligent non-contact sensorresponse systems, and non-contact object or target data programming anddata retrieval. The disclosure may also be applied to systems requiringnon-contact alignment capability, for example, dental and medical x-rayand imaging technologies. In addition, the disclosure is relevant tonon-contact detection, monitoring, control or feedback for the specificalignment of certain systems and components of systems that would beenhanced by a remote alignment or positioning capability.

The system of the present disclosure is particularly applicable in theactivity of proper positioning of a given x-ray machine “gun” or “head”apparatus to a given x-ray film apparatus. The system utilizes a simplenon-contact alignment procedure without the need for implementing“customary” alignment devices or techniques. The system is applicable tonewer technology (for example, digital radiography) and to establishedtechnologies, such as x-ray film and x-ray holder devices. As a functionof operation, the present disclosure has the capacity to be utilized inmany applications, wherein, and broadly speaking, an “RF tag” device(minimally composed of a carrier-receive/data-transmit coil, a resonancecapacitor, a power conditioning circuit, a microcontroller, and a coilshunting circuit) acts as a “remote target/sensor” or “system activationkey.” The RF tag is configured to interface with an “RF interrogator”device, minimally composed of a carrier-transmit/data-receive coil, aresonance capacitor, a carrier signal drive circuit, an applieddata-receive signal detection circuit, various applied data-receivesignal filters, various applied data-receive signal amplifier circuits,and various logic devices or a microcontroller wherein the RF tag and RFinterrogator, together, create a non-contact RF transducer alignmentfunction and system. The system is configured such that when the RFinterrogator is in the near presence of the RF tag, then the RFinterrogator ultimately causes to occur one or more predefined actionsor activities. Such actions may be determined by the real-worldfunction(s) desired, application, and the type of end-user productmanufactured.

The present disclosure provides for a non-contact RF transducer systemminimally composed of at least one RF tag device and a controlelectronics package, such as an RF interrogator. Together, the RF tagand RF interrogator act to minimally perform as other RFID systems, yetmay also provide for an RF transducer a non-contact “alignment” system.The RFID system of the present disclosure may be adapted for use as anintelligent “item or device detector,” an electronic non-contactpass-key system, a medical history bracelet antenna system, a computerenable apparatus, and a keyless car door and trunk opening system, asexamples. As may be appreciated by those of ordinary skill in the art,many other applications for non-contact RFID sensor alignment exist thatmay benefit from a system configured to detect, monitor, and respond tothe particular alignment of one apparatus to another. Such applicationsinclude when space docking one vehicle or platform to another, locatingthe internal communications port on a marine environmental transducer sodata can be recovered from the transducer without opening its enclosureor using an external connector, and for use in exactingly monitoring thepositioning of various hatches or flight-control surfaces, etc., oncommercial aircraft.

Numerous hand-held applications are apparent, for example, exactinglyidentifying the position of in-wall, underground or buried cabling orgas pipes, and the like, wherein homeowners and utility personnel couldeasily denote not only the “where” and “what” of what lies hidden fromview, but perhaps, when installed or how deep, by using one or moreconcealed RF tag devices. Another hand-held application includes aluggage identification system, wherein ticket handlers may cause theprogramming and attachment of an RF tag to luggage. The benefit of sucha system includes far more accurate and simple destination processing,and may also include insuring the rightful owner during baggage “pickup”should a question arise.

One benefit of the present disclosure is demonstrated when an RF tag isplaced behind a given non-transparent material, and so not normallyvisible to a user/operator of the present disclosure, the user/operatormay utilize the RF interrogator to locate the RF tag (or vice versa).The RFID system may be used to locate the hidden RF tag and to alsoeasily identify a “best-alignment” (of the RF tag to the RFinterrogator) scenario as well, if the latter is desired. In essencethen, the RF interrogator is, or may be, intended to identify the bestposition of, or “line-of-sight” of the RF tag to the RF interrogator forthen performing certain predefined activities. In some instances, the RFtag may or may not actually be hidden from view of the user/operator.Thus, if alignment of the RF tag to the RF interrogator is required, andif the alignment procedure is left solely to a human, wherein one mightuse a best guess or estimation process, and if the alignment isconsidered critical, then errors can occur in the attempt for alignment,providing the processes generally insure a “best-alignment” scenariofails to occur.

The potential disadvantages of humanly performed alignment activitiesare overcome by the present disclosure, in that the present disclosureand RF interrogator component thereof automatically identifies a“best-alignment” scenario for a user/operator. In other applications,exacting alignment between the RF tag and RF interrogator may at timesnot be critical, and that simple RF tag detection is all that isrequired. In other applications, perhaps utilizing a hand-held RFinterrogator unit, retrieving certain data a perhaps hidden RF tag maybe keenly desired when the hand-held RF interrogator is within “reading”distance of a given RF tag. In many such instances, less than perfectalignment between a given RF tag and an RF interrogator is whollyacceptable and practical, as the present disclosure can easily allow fornon-critical RF tag alignment detection and readings.

Another example of an application of the system of the presentdisclosure includes locating and identifying hidden control knobs orvalves and/or buried coupling devices. Such an application requiresexacting location of such devices in order that one may accuratelyunveil the devices' physical view before servicing or repairing orupgrading may be accomplished.

The present disclosure and its two main components (an RF tag device,and an RF interrogator device) provide for one or more embodiments ofthe RF tag device. The RF tag remains minimally composed of: 1) an LCtank circuit, having at least one carrier signal receive/data transmitcoil of a predetermined value; 2) a resonant capacitor of apredetermined value to work in parallel with the carrier signalreceive/data transmit coil, wherein both collectively act in response toa predefined applied carrier signal, so as to be caused to resonate withthe applied transmit carrier signal; 3) a power conditioning circuit,wherein a portion of the resonant energy generated by the LC tankcircuit is used to create the required operating power for; 4) anon-board microcontroller device, wherein the microcontroller device canbe configured to identify certain of the RF tag's operationalparameters, and whereby a predetermined serial data stream may begenerated from a predetermined protocol by using; 5) a carrier signalreceive/data transmit coil shunting circuit; or 6) an LC tank circuitshunting circuit. As may be appreciated by those skilled in the art,present technology provides that an RF tag device does not require abattery for operation, but instead remains responsive to a near or closeproximity externally applied carrier signal and of a frequency that isconducive to cause resonance of a given RF tag's LC tank circuit.

The RF interrogator may be a wall powered or battery operated device.The present disclosure provides for one or more embodiments of the RFinterrogator device, wherein the RF interrogator remains minimallycomposed of: 1) an LC tank circuit, composed of at least one carriersignal transmit/data receive coil of a predetermined value; and 2) aresonant capacitor of a predetermined value to work in parallel with thecarrier signal transmit/data receive coil, wherein both collectively actin resonance to create a predefined applied carrier signal; when 3) apredetermined carrier drive signal is applied thereto; 4) an RF tagsignal-detection circuit, the obtained signal of which is applied to; 5)predetermined filters and amplifier circuits, the resultant signal ofwhich is then applied to; 6) a microcontroller device configured orprogrammed for desired operations and functions, as well as the abilityto read the serial data transmitted by a given RF tag, whereby; 7) themicrocontroller may cause to occur certain predetermined real-worldactivities, predicated on its associated predetermined firmware andinput/output (I/O) circuitry and specific application or need.

Another aspect of the system of the present disclosure is to provide forremote placement of the interrogator carrier signal transmit/datareceive coil from the RF interrogator electronics package, therebyproviding a third main component of the system. Such a featureaccommodates more easily the placement of the RF interrogator coil(hereinafter referred to as “RF antenna” or RF antenna device) in agiven “work area.” This aspect may be accomplished through theattachment of a pre-configured cable between the RF interrogatorelectronics package and its associated carrier transmit/data receivecoil or RF antenna. The system also provides for detecting anddisplaying the distance, within certain predefined limits, of the RF tagto the RF interrogator carrier transmit/data receive coil. The systemfurther provides the user with a visual indication of when the RFinterrogator detects the RF tag. Such detection can act to wake a“sleeping” RF interrogator microcontroller or wake an RF interrogatormicrocontroller that resides in “idle” mode. This feature also providesfeedback to the user/operator that an RF tag detection has occurred. Thevisual indication is perhaps best accomplished with an LED (lightemitting diode), particularly in terms of indicator life longevity andvibration resistance. The system may also provide the user with aseparate visual indication of when the RF interrogator detects areadable or valid data stream from a given RF tag. Predicated on dataprotocol and other data-form factors, such detection can act to cause anRF interrogator microcontroller to ascertain the RF tag data stream tobe valid and, thus, reliably useable. This feature also providesfeedback to the user/operator that a given RF tag “reading” by the RFinterrogator may be in process.

It is also a function of the present disclosure to provide for thoseinstances wherein one or more audio tones are desirable or required. Anaudio tone generator may provide additional feedback to theuser/operator that tag detection or reading has occurred, for example,without need for the user/operator to look away from where or what he orshe is presently (visually) focused on. The audio tone generator maysimply provide for singular tone structures, or may providepitch/frequency or volume changes (predicated, for example, on RF tagdistance) and may offer voice feedback or commands. The system may alsoprovide for RF tag detection with valid RF tag data-stream visualindicators and for an audio speaker device at or in close proximity tothe RF interrogator carrier transmit/data receive coil.

The system of the present disclosure may further be configured with adisplay device, such as a liquid crystal or OLED display. Such a displaydevice may act to provide a user/operator with such predefined detailsas instructions, captured RF tag information, and other operationalinformation. The system may be further configured to allow an RFinterrogator to interface with a computer and printer so as to remotelycapture, display, and record some or all the information in a given RFtag.

The system of the present disclosure may be configured to provide forvariable RF carrier transmit signal frequency control so as to utilizevarious RF tags by various manufacturers, having varying frequencies ofresonance. Variation of the RF carrier transmit signal frequency can beimplemented with an adjustment potentiometer or by a keyboard entry.Other mechanisms may be used, such as the switching in and out ofvarious resonance capacitors by altering the divide-by rate of certainlogic devices, by a tunable coil device, or a combination thereof.

In addition, the system of the present disclosure may be configured tovisually or audibly indicate when power has been applied to the RFinterrogator. Similarly, the system may visually or audibly indicatewhen a predefined warm-up period has elapsed and system stability hasoccurred. Such a feature is perhaps most desirable when a givenelectronics circuit utilizes a clock or oscillator circuit.

The system of the present disclosure may also visually or audibly, orboth, indicate maximum (or even perhaps, less than maximum) carriertransmit signal strength or amplitude. The system may further allow fordisplaying the carrier transmit signal frequency, whether based upon anLED array or by using an alphanumeric or graphics display of somenature. In addition, the system may be configured with variousmechanisms to provide for indication of the presence of the carriertransmit signal and to provide for indication of the presence of thecarrier transmit/data receive coil.

Further, the system of the present disclosure may provide selectablecarrier transmit drive signal waveform control. The carrier transmitdrive signal control may allow for the use of sine triangular or squarewaves, pulse width modulation or other signal waveform structures. Thesystem may be configured to provide for carrier transmit drive signalfrequency tuning and detuning control circuitry. Predicated on thenature of a given carrier transmit drive signal waveform and itspotential harmonics, the system may allow signal tuning and detuning soas to achieve a “best-case” resonant waveform.

Another aspect of the system of the present disclosure is to provide foron-the-fly and in-situ programming of a given RF tag. One suchapplication is wherein a dentist utilizes the system of the presentdisclosure to take a molar x-ray. Accordingly, the customary “rimholder” (used to both hold the x-ray film and assist in x-ray headalignment) may be replaced with an intelligent mouth x-ray film RF tagdevice. The system may be configured such that the dentist's RFinterrogator to identify a “best-alignment” for taking an x-ray. As thedentist's RF interrogator indicates a valid “read” of the RF tag (beforeor after the RF tag has been placed in the patient's mouth), the dentistcould type in certain information on a keyboard of which he or shewishes to be programmed into the intelligent mouth x-ray film RF tagdevice, such as a patient's name, date, and/or client number. Thatparticular x-ray film RF tag may remain permanently programmed and bedirectly traceable to that patient.

The system of the present disclosure may have other features, such as toindicate whether a given RF interrogator is in a particular mode ofoperation, for example, data programming mode, tag detection oralignment mode, or idle mode. Other features of the system mayinclude: 1) the capability of the RF interrogator circuitry to provideindication of “best-alignment” without the need for utilizing customaryalignment tools, devices, or procedures; and 2) to do so in anon-contact manner, as in the above dental example where two netbenefits and results are: a) less complication for the dentist; and b)an enhanced comfort factor for dental patients.

Additional embodiments of the system of the present disclosure can beconstructed such that the system may allow for those applicationswherein a particular location must be reliably identified inthree-dimensional space. For example, three RF tags may be used in an“x”, “y” and “z” axis configuration that are configured to interfacewith a triple-coil RF interrogator device also configured for “x”, “y”and “z” axes. Further, the “x”, “y” and “z” axes may or may not berelative to the predetermined positioning of the triple-coil RFinterrogator device or the predetermined positioning of the three RFtags. Such a system may be beneficial if the “x”, “y” and “z” axes ofthe RF tags or RF interrogator (or both) are required to be absolute orare allowed to reside at non-absolute angles/attitudes in free space. Inthis manner, the “x”, “y” and “z” axes for either the RF tags or thetriple-coil RF interrogator may be utilized as fixed or variable. If oneor the other components of the system (the RF tag or RF interrogator, orboth) are desired as variable, then the system offers significantrepositionability and can be variably indexed about a full 360 degreelocus. Accordingly, three RF tags and three RF interrogators could beemployed so as to work as a single collective transducer apparatus oremployed so as to function as three independently positionabletransducer apparatus-sets. Each transducer apparatus-set may beconfigured to be positioned upon a separate predetermined or variableaxis or plane. Alternatively, a single RF interrogator device could beused, wherein it remains configured to utilize three carriertransmit/data receive coils of the same or differing sizes and carrierfrequencies. Where this 3-D function is used with various imagingtechnologies (for example, radiation treatments and laser surgery)medical equipment alignment and/or procedural site loci, identificationis important to both doctor and patient.

Furthermore, the system of the present disclosure may be configured withthe capacity to allow for exacting data programming of the RF tags forsimple or specific utility, for example, patient processing. Theprogramming may allow for such information as patient identification,allergy or medication warnings, past medical history, reason foradmittance, date of admittance, procedure(s) to be performed, patientname, as well as patient age, date of birth, diet type, debilities, etc.

Additionally, the system of the present disclosure can be constructed invarious sizes and with various features. Alternative embodiments of thesystem can be configured such that the system may address suchapplications as latch-key kids and intelligent door lock systems(eliminating the need for physical keys); gardening/plant/crop/tree I.D.markers (which might also provide for feeding and care instructions);personal medication allergy warning bracelets; patient medical historyor processing tags; product history tags (with particular utility asregards warranty-period initialization or product tracking); newborntracking and I.D. tags (which can assist in eliminating “swapped”newborn errors, as well as provide for accurate caretaker/parent access,or the setting off of alarms when an attempt to otherwise hold or removea child has occurred); land boundary or corner markers (particularlyuseful with regards to certain mining “claims”); pet access tags(allowing a pet access to or from a home or yard at particular times ofday, as an example); vehicle and vehicle compartment entry systems;computer access systems; traveler luggage control and managementsystems; utility, gas, and water line detection systems; ballpark,entertainment, and transit pass systems; medical diagnosis, imaging, andradiation systems; laser surgery systems; and of course, all manner ofx-ray systems, to mention a few. Given such potential real-worldapplications, it is therefore the intended purpose of the presentdisclosure to offer a new, uncomplicated, utilitarian, reliable, andinexpensive yet intelligent and precise means of non-contact sensoralignment as pertains to RF tag devices and RF interrogator devices,which herein together, now provide for a novel RFID transducer systemfor critical-alignment as regards x-ray and medical applications, aswell as those myriad applications wherein the issue of “alignment” isnot a critical one.

Referring now to FIG. 1 and item 8000 in particular, the figurerepresents a physical system block diagram of an embodiment of an RFIDtransducer alignment system providing for an altogether new RFIDapplication and market, and, the general enhancement of common RFIDsystems according to the present disclosure.

Referencing FIG. 1, item 1000, referred to herein as “RF interrogator”and “RF interrogator means,” is an assembly caused to be attached toitem 2000, referred to herein as “RF antenna” and “RF antenna means,” bymeans of a predetermined cable apparatus, item 4000, referred to hereinas “antenna umbilical cable” and “antenna umbilical cable means.” Item3000, referred to herein as “RF tag” and “RF tag means”, remains thefinal subsystem component of the RFID transducer alignment system but isin no way attached to any other component of or within the system.

Generally speaking, when items: 1000 (the RF interrogator), 2000 (the RFantenna) and 4000 (the antenna umbilical cable) have been assembled, andwhen item 1000 (the RF interrogator) is then enabled, by means of apredetermined power switch and applied power source, item 2000 (the RFantenna) will predeterminedly begin RF emissions, and at a predeterminedfrequency, of 100 kilohertz or greater, resulting in a radiated RF fieldof flux from item 2000 (the RF antenna).

When the RF tag 3000, also constructed to oscillate at a predeterminedfrequency of 100 kilohertz or greater, and which frequency is ultimatelycaused to be near or identical to that of the RF antenna 2000, and whenbrought within a predetermined distance of the RF antenna 2000, the RFemissions of the RF antenna 2000 will cause the LC tank circuit of theRF tag 3000 (more fully depicted in FIG. 4), to begin to self-oscillate.

As the LC tank circuit of the RF tag 3000 begins to self-oscillate,internal power for the RF tag 3000, is created by an internal powerconditioning circuit, and ultimately, a serialized data stream isgenerated by an associated and integral microcontroller device. Theserialized data stream is applied to the LC tank circuit, which thenprovides the effect of dampening the oscillations of the RF tag coil.

Therefore, and as the LC tank circuit of the RF tag 3000 begins toself-oscillate, RF emissions are predeterminedly created therefrom,which can be observed to be impressed with serialized data from theassociated and integral microcontroller device means. In essence then,the RF emissions from the LC tank circuit of the RF tag 3000, becomemodulated by the serialized data stream.

As the above occurs, the resonating RF emissions signal created by RFantenna coil 2002 of the RF antenna 2000, now being impressed with areturn RF emissions signal containing modulated serial data from the RFtag 3000, can be observed to have both a reduced amplitude and tocontain a representation of the modulated serialized data. The RFinterrogator 1000 containing certain circuitry that can detect, filter,and amplify the serialized data, then transforms a resultant signalthereof into a viable and useable data stream signal, in effectreconstructing the original data stream as provided by the RF tag 3000.

The viable and useable data stream signal is then applied to, and readby, a microcontroller device within the RF interrogator 1000, andminimally predicated on application and predetermined firmware, the RFinterrogator 1000, then performs certain desired real-world functions,one of which is that of indicating whether or not a critical alignmentcondition of the RF tag to the RF antenna exists, and by various means,which include, but are not limited to visual or audio means, or acomputer apparatus 6000 or a printer apparatus 7000.

The following descriptions provide yet further detail with regard toFIG. 1, and as relates to each main sub-system component of the presentdisclosure.

Now referencing FIG. 2, one will note multiple circuit sections withinthe block identified as 1000, “RF interrogator,” wherein there isillustrated the five main circuit components to the RF interrogator,identified as a power control circuit 1500, microcontroller core circuit1100, user input and feedback circuit 1300, analog front-end 1400, andantenna control circuit 1200.

Three of the five main circuit components, noted as power controlcircuit 1500, microcontroller core circuit 1100, and user input andfeedback circuit 1300, remain entirely non-complex, and can beconstructed by various means in various ways to provide the functionsindicated. Intensive detail therefore, is not felt required of these thethree main circuit components; thusly, abbreviated descriptions thereofwill more than adequately suffice.

However, and as may not be clear to those skilled in the art, the lasttwo of the five main circuit components, noted as analog front-end 1400and antenna control circuit 1200, remain not only as aspects of thepresent disclosure, but remain somewhat complex in nature. Thereforethese last two main circuit components require more explicit detail forfully understanding the present disclosure, and such detail will alsofollow.

To begin, and referencing both FIGS. 1 and 2, a predetermined connectorapparatus 1001 accommodates a predetermined applied external powersource 5000 wherein at least one predetermined power potential maygenerally be applied to the power control circuit 1500 and,specifically, to the power conditioning circuit 1500-A, whereby one ormore predetermined voltage potentials may be created for use by theremaining circuits of the RF interrogator 1000.

The power conditioning circuit 1500-A provides for an applied powerswitching device 1500-D, allowing for application control of the appliedpower source, whether that source be internal or external, to theremainder of the power conditioning circuit 1500-A. Also a part of thepower control circuit 1500, and as an option to utilizing the appliedexternal power source 5000, a predetermined battery device 1500-C, maybe used, if desired, being particularly beneficial in certain hand-heldembodiments and applications of the present disclosure.

In those applications where external power source backup or occasionalfreedom from an external power source is desired, provisions for abattery charging circuit 1500-B are additionally made available tocharge the battery device 1500-C during those occasions when appropriateto do so and when the applied external power source 5000 is madeavailable.

In whole then, the power control circuit 1500 may provide for either orboth an externally applied power source, an internally supplied powersource, and ultimately the voltage potentials that operate the whole ofthe RF interrogator.

The microcontroller core circuit means 1100 provides for amicrocontroller device 1100-A, a microcontroller (μC) oscillator circuit1100-B, a microcontroller (μC) reset circuit 1100-C, and an external I/Ocontrol circuit 1100-D.

The microcontroller device 1100-A provides for multiple functions, notlimited to, but including those functions of certain I/O ports and/orpins, internal RAM and ROM or E2 memory, etc., an internal clockgenerator, reset control, at least one internal timer, and perhaps, anA/D converter.

The microcontroller (μC) oscillator circuit 1100-B may be composed of acrystal oscillator device and two capacitor devices, typically providingmeans not only for enhanced oscillation stability over temperature, butfor a broad range of frequencies at which the microcontroller device1100-A may operate or remain (potentially) constructed of a resistordevice and a capacitor device in series, providing means for reducedoscillation stability over temperature, and a minimum frequency at whichthe microcontroller device 1100-A may operate.

The microcontroller (μC) reset circuit 1100-C may be constructed of aresistor device and a capacitor device in series, provides means for themicrocontroller device 1100-A to note when adequate operational power isdependably available, as well as allows the microcontroller device1100-A to detect or determine when to reset various internal registersin preparation for proper operation to occur.

The external I/O control circuit 1100-D may be constructed of simplelogic-gate devices or communications port function-specific I/O devices,such as serial or parallel communications devices, wherein themicrocontroller device 1100-A may effect communication to or withcertain external devices, such as a remote printer apparatus 7000 or aremote computer apparatus, 6000, per predetermined external connectorapparatus 1003 and 1002, respectively.

The user input and feedback circuit 1300 provides for a user keyboardapparatus 1300-C, a user LCD (or other “like” display) apparatus 1300-D,an LED (light emitting diode) display 1300-E, an audio control circuit1300-B, an audio device 1300-F, and a user input/output (I/O) controlcircuit 1300-A.

The user I/O control circuit 1300-A, in effect a signal multiplexer, isconstructed so as to allow means wherein certain discrete logic signalsor data bus signals, etc., can be steered to or from, and between themicrocontroller device 1100-A and the user keyboard apparatus 1300-C,the user LCD (or other “like” display) apparatus 1300-D, the LED (lightemitting diode) display 1300-E, and the audio control circuit 1300-B.

Further, the user I/O control circuit 1300-A may be generallyconstructed of simple logic gate devices or one or more (perhapstri-state) 8-bit latch or bus circuit devices, so as to provide meansfor the microcontroller device 1100-A to interface with the userkeyboard apparatus 1300-C, user LCD (or other “like” display) apparatus1300-D, LED (light emitting diode) display 1300-E, and the audio controlcircuit 1300-B, when need be, and with the benefit of requiring only aminimized quantity of I/O or port pins on the microcontroller device1100-A.

The user keyboard apparatus 1300-C enabled by the user I/O controlcircuit 1300-A, and generally constructed of two or more push buttonswitches, provides means for a given user to input certain predetermineddata, instructions, and commands, etc., to the microcontroller device1100-A.

The user LCD (or other “like” display) apparatus 1300-D, enabled by theuser I/O control circuit 1300-A, provides means for a given user to noteinputted user data or instructions or commands, etc., to themicrocontroller device 1100-A as well as obtain feedback related touser-inputted information and certain other data or predeterminedoperational parameters as may be provided by the RF interrogator 1000and the RF transducer alignment system 8000.

Further, the user LCD (or other “like” display) apparatus 1300-D mayalso provide additional means required for a backlighting function,particularly beneficial for RF transducer alignment system operation indimly lit areas.

The LED (light emitting diode) display 1300-E enabled by the user I/Ocontrol circuit 1300-A, and composed of one or more LED devices and acurrent limiting series resistor device for each installed LED device,provides quick feedback for a given user, whereby one can note certainpredetermined operational parameters of the RF interrogator 1000 and theRF transducer alignment system 8000, such as when a “ready to operate”state has been established or when a given RF tag is detected, and otherparametric nuances as required by application or as desired.

Further, one or more certain signals of the LED (light emitting diode)display 1300-E may additionally be passed on to a connector device 1004so that the signals may then be passed through the antenna umbilicalcable 4000 to the RF antenna means 2000, and (now referencing FIG. 3)through a connector apparatus 2001 to the user feedback circuit 2003 andultimately to the LED display 2003-B (also of FIG. 3).

Referring again to FIG. 2, the audio control circuit 1300-B, enabled bythe user I/O control circuit 1300-A, may be composed of a simple FETtransistor, or like device, or a gated tone or voice generator circuit,of which, and in either case, a signal thereof is ultimately passed tothe audio device 1300-F so as to create an audible source of feedbackfor a given user and as may additionally concern specific systemparameter detection.

The audio device 1300-F may be comprised of a standard speaker elementor a piezo device.

Further, a signal of the audio control circuit 1300-B may additionallybe passed on to a connector device 1004 so that the signal may then bepassed through the antenna umbilical cable 4000 to the RF antenna 2000and (now referencing FIG. 3 again) through a connector apparatus 2001 tothe user feedback circuit 2003 and ultimately to the audio device 2003-A(also of FIG. 3).

Referencing FIG. 2 once again, the three non-complex circuit componentsof the RF interrogator 1000, include the power control circuit 1500,which both receives and applies the voltage potential necessary forproper operation of the RF interrogator 1000; the microcontroller corecircuit 1100-A, which provides the intelligence and means to allowdesired functionality of the RF interrogator means 1000; and the userinput and feedback circuit 1300, which provides for allowing intimateuser control of, and feedback from, the RF interrogator 1000.

Referring now to FIGS. 1 and 3, the RF antenna 2000 is described. The RFantenna 2000, is composed of a connector apparatus 2001, which allowsfor applying certain circuit signals from the RF interrogator means 1000to the RF antenna means 2000, as well as for applying certain circuitsignals from the RF antenna 2000 to the RF interrogator 1000; an RFantenna coil 2002; and a user feedback circuit 2003.

An input signal 11, a third applied signal, carries one or morewaveforms or frequencies, which become audibly notable as sound whenpresented to a first pin of item 2003-A, an audio device, of userfeedback circuit 2003. The audio device 2003-A may be comprised of astandard speaker element or a piezo device.

Input signal 12, a fourth applied signal, is presented to a first pin ofa first LED device of item 2003-B of user feedback circuit 2003 toindicate RF tag detection has occurred.

Input signal 13, a fifth applied signal, is presented to a first pin ofa second LED device of item 2003-B of user feedback circuit 2003 toindicate that a valid data stream signal has been detected.

Input signal 4A, a sixth applied signal, is presented to the remainingand second pins of the audio device 2003-A, the first LED device of item2003-B, and finally, the second LED device of item 2003-B, all of userfeedback circuit 2003, providing for a second circuit ground signal.

Input signal 3, a first applied signal, composed of a predeterminedfrequency when active, is presented to a first lead of an RF antennacoil apparatus 2002 of the RF antenna 2000, as means to allow foreventual resonant oscillation of the RF antenna coil apparatus 2002. Asthe RF antenna coil apparatus 2002 then responds to applied the inputsignal 3, a first EM field of flux and carrier transmit EM field of fluxsignal is created by the RF antenna coil apparatus 2002.

Output signal 5, a first return signal, is presented to the connectorapparatus 2001 as means to allow for monitoring the eventual resonantoscillations of the RF antenna coil apparatus 2002 by the RFinterrogator 1000.

Input signal 4, a second applied signal, is presented to a second leadof an RF antenna coil apparatus 2002 of the RF antenna 2000, providingfor a first circuit ground signal.

Output signal 7, a second return signal, is presented to the connectorapparatus 2001 as means to enable monitoring the presence of the RFantenna coil apparatus 2002 within the RF transducer alignment system8000 by the RF interrogator 1000.

Referring now to FIGS. 1 and 4, the RF tag 3000 is described. The RF tag3000 is composed of a microcontroller (μC) core circuit 3001 formed of aμC oscillator 3001-B, a μC reset circuit 3001-C, and a microcontrollerdevice 3001-A; an RF tag LC tank circuit 3002 formed of an RF tagresonant capacitor device 3002-A, and an RF tag coil apparatus 3002-B;and finally, a power conditioning circuit 3003.

The RF tag 3000, is a stand-alone apparatus that requires no on-board orattached power source for operation. As also indicated, power for the RFtag 3000, is obtained when the RF tag 3000 is brought within closeproximity to a first radiated EM field of flux, as would typically beprovided by the RF antenna 2000, such that the RF tag LC tank circuit3002 becomes impressed with the first radiated EM field of flux, whichthen excites the RF tag LC tank circuit 3002 into self-oscillation,which as a result, produces a localized second EM field of flux.

The second EM field of flux, produced by the RF tag LC tank circuit3002, is then radiated from the RF tag LC tank circuit 3002 and the RFtag 3000.

A portion of the energy created by the second EM field of flux producedby the RF tag LC tank circuit 3002 is then applied to the powerconditioning circuit 3003 composed of a rectifier circuit and acapacitor device, whereby a second internal signal and circuit groundsignal 36 are created. A predetermined voltage potential of a D.C.nature is created, all of which is then applied, via a first internalsignal 35 to the microcontroller device 3001-A, providing foroperational power.

When the microcontroller device 3001-A asserts the predetermined voltagepotential to be stable, the microcontroller device 3001-A begins todampen the oscillations produced by the RF tank LC circuit 3002 by meansof applying a predefined and “stored” data stream signal to the base ofan internal FET transistor device, thereby enabling the FET, whose drainand source pins are, effectively, placed across third and fourthinternal signals, 33 and 34, respectively. By virtue of physicalattachment and the enabled FET, the impresses the second EM field offlux produced by the RF tag LC tank circuit 3002 with the “stored” datastream signal, culminating in a modulated second EM field of flux and adata transmit or return EM field of flux signal.

Because the construction and operation of items 3001-B and 3001-C havebeen generally described earlier, and as related to the RF interrogatoritems 1100-B and 1100-C, respectively, repeat discussion is unnecessary.Suffice it to say, item 3001-B provides means by which themicrocontroller device 3001-A might obtain a system clock signal foroperation, and that item 3001-C provides means by which themicrocontroller device 3001-A might obtain a reset signal so as to beginoperation.

Turning next to the antenna control circuit 1200 and analog front-endcircuit 1400, the remaining two, and more complex, circuit components ofthe RF interrogator 1000.

Referring to FIG. 2 for an overview, and referencing FIG. 5 for clarityof this section, one will note item 1200, the antenna control circuit iscomposed of antenna transmit waveform control and drive circuit 1200-A,and antenna resonant capacitor 1200-B.

The antenna transmit waveform control and drive circuit 1200-A providesmeans whereby a predetermined square wave signal, in this embodiment, isgenerated by item and circuit component 1208, a comparator device, anditems and circuit components 1201 through 1207, which together providefor the antenna transmit waveform control portion of the antennatransmit waveform control and drive circuit 1200-A.

The comparator device 1208 is gated, and thus enabled or disabled, bymeans wherein resistor 1205 is made responsive to a selected output pinand signal 10A from the microcontroller device 1100-A, wherein a firstand left lead and input to resistor 1205 is alternatively pulledlogically Hi or LO.

Resistors 1205 and 1206 create a center voltage potential of ½ of theapplied circuit voltage, in this embodiment of 2.5 volts D.C., when thefirst and left lead and input to resistor and item 1205, is pulledlogically HI. The center voltage potential, for example 2.5 volts,becomes the baseline for oscillation to occur about the comparatordevice 1208. When the first and left lead and input to resistor 1205 ispulled logically LO, the comparator device 1208 is disabled fromoscillating.

If gating the comparator device 1208 is not required for a particularapplication or embodiment, the first and left lead and input to resistor1205 may be tied directly to +5V instead.

Resistors 1202 and 1203 and capacitor and item 1201 provide means foractual oscillation about the comparator device 1208 to occur.

As illustrated, resistor 1203 is programmably made to be variable,wherein the actual resistance value of resistor 1203 is intimatelycontrolled by pin G, noted as signal 10, from the microcontroller device1100-A, and thus ultimately provides for variation in the oscillationfrequency about the comparator device 1208, which, based on thecomponents illustrated, allows for an oscillation and frequency range ofapproximately 113 kilohertz to 165 kilohertz. For this embodiment itshould be noted the selected frequency of oscillation was set to 119.5kilohertz.

As well of note, resistor 1203 can alternatively be replaced with amanual variable-resistor device.

Because the circuit component 1208, the comparator device, allows onlyfor an open-collector transistor output, which provides for a logical LOstate and output signal when turned on, resistor 1204, a pull-up device,must be installed to accommodate a logical Hi state and output signalwhen the open-collector transistor is turned off, which collectivelythen provides for the required two-state duty cycle.

Thus, the collective junction of the open-collector transistor output ofthe circuit component 1208, the comparator device, and the resistors1204, 1203, and 1207, provide not only for the required two-state dutycycle, but an oscillating circuit signal 14 of 119.5 kilohertz, havingthe form of a square wave.

For an alternative embodiment, circuit components 1201 through 1208 canbe wholly replaced by a crystal clock oscillator circuit and a divide-bycircuit, as an example, which together, can also provide for a squarewave output. However, frequency changes, if desired, are limited andmade more difficult, in that by the very nature of such the circuitryonly fundamental harmonics of the crystal oscillator can be easilyrealized, to with: f, f/2, f/4, etc.

As an example, the output of a 4 megahertz crystal oscillator circuitapplied to a divide-by 32 logic device will easily provide for a 125kilohertz square wave output, but it will not easily accommodateproviding for a 119.5 kilohertz square wave output. Neither will thelogic device, set to divide by 16, or divide by 64, accommodateproviding for a 119.5 kilohertz square wave output.

The square wave signal 14 is then applied to the input of circuitcomponent 1209, an inverter device, which inverts the square wavesignal. This resultant signal 6 is then applied to the inputs of twofollowing inverter devices 1210 and 1211 so as to buffer the resultantsignal 6 and perform a signal phase correction.

The output of circuit component and item 1211, noted as signal 8, isthen fed back to an input pin A of the microcontroller device 1100-A soas to provide means whereby the oscillation frequency of the circuitcomponent and item 1208 can be monitored.

The circuit component 1210 through its output, noted by signal 1,provides for the antenna transmit waveform drive portion of the antennatransmit waveform control and drive circuit 1200-A, whereby the outputsignal 1 is fed forward and applied to a first pin of a predeterminedantenna resonant capacitor 1200-B.

The remaining and second pin of the antenna resonant capacitor 1200-B isultimately made to connect to a first lead of an RF antenna coil 2002 bymeans of circuit signal 3 and connector apparatus 2001, whereuponoscillations of the predetermined frequency can be observed when theremaining and second lead of the RF antenna coil 2002 is connected tocircuit ground through circuit signal 4 and the connector apparatus2001.

The output signal 2, identified by the nomenclature “SIGOUT,” alsoattached to the remaining and second pin of the antenna resonantcapacitor 1200-B, provides means by which the oscillations of apredetermined frequency upon circuit signal 3 can be passed on to thatcircuitry identified as analog front-end 1400 of FIG. 2, and inparticular, to the anode of the diode 1401 of FIG. 6, of a signaldetection circuit 1400-A, which will collectively be discussed shortly.

As expected, the output signal 2, which is exactly the same as thecircuit signal 3, is fundamentally a sine wave and remains of analternating voltage potential, which greatly exceeds that of the antennatransmit waveform drive signal 1. Component values and resonance factorsof both the antenna resonant capacitor 1200-B and the RF antenna coil2002, working in synchronicity with each other, and, depending on thefrequency of oscillations supplied by signal 14, together provide meansfor the amplitude exacerbation observed in the output signal 2.

In fact, peak-to-peak voltages of greater than 150 volts can be observedin output signal 2 when maximum resonance is sought. However, and forbest operation disclosure, the frequency of oscillations supplied bysignal 14 are generally made to be detuned by about 7% from theinherently derived resonant frequency, as calculated by standard LCresonance equation [i.e., ½π√LC] and the actual values of the antennaresonant capacitor 1200-B and the RF antenna coil 2002, which, and alsoas expected, somewhat reduces the amplitude of the circuit signal 3 andthe output signal 2, yet does not affect or negatively impact operationof the interrogator 1000 in any way.

There is a portion of FIG. 5 that contains a schematic of the RF antennacircuit 2000, which therein provides for a multiplicity of input/appliedand output/return signals at the connector apparatus 2001, as addressedearlier in this section.

Internal circuit signal 7 of the RF antenna circuit 2000 provides meanswhereby the RF interrogator 1000 might monitor the presence of circuitsignal 4 and the RF antenna circuit 2000, and particularly, the presenceof the RF antenna coil apparatus 2002, so as to typically either noteand indicate the lack of a main sub-system component, and so at aminimum disable the comparator device 1208, or proceed into normaloperations and enable the comparator device 1208.

If the antenna umbilical cable apparatus 4000 is attached to item 1004,a predetermined connector apparatus and component of the antenna controlcircuit 1200 and, if the RF antenna circuit 2000 is attached to theantenna umbilical cable apparatus 4000, then the internal circuit signal7 of the RF antenna circuit 2000 will be presented to the antennacontrol circuit 1200 and to the resistor component 1218, as well as tothe input of the inverter device 1212. The output of the inverter device1212 will then be forced logically Hi, indicating to the microcontrollerdevices 1100-A by means of signal 9 being presented to the μC input pinB that the RF antenna circuit 2000 is indeed present.

However, if the antenna umbilical cable apparatus 4000 is not attachedto the connector apparatus 1004 or if the RF antenna circuit 2000 is notattached to the antenna umbilical cable apparatus 4000, then theinternal circuit signal 7 of the RF antenna circuit 2000 will not bepresented to the antenna control circuit 1200 and to the resistorcomponent 1218, as well as to the input of the inverter device 1212. Inthis case, the output of the inverter device 1212 will then be forcedlogically LO, indicating to the microcontroller devices 1100-A by meansof signal 9 being presented to the μC input pin B that the RF antennacircuit 2000 is absent.

As well, internal circuit signal 5 of the RF antenna circuit 2000provides means whereby the RF interrogator 1000 might monitor thepresence of the circuit signal 3 and the eventual resonant oscillationsof the RF antenna coil apparatus 2002 of the RF antenna circuit 2000 soas to typically note and indicate the lack of the eventual resonantoscillations or note and indicate the frequency of the eventual resonantoscillations or both.

If the antenna umbilical cable apparatus 4000 is attached to theconnector apparatus 1004, and if the RF antenna circuit 2000 is attachedto the antenna umbilical cable apparatus 4000, then the internal circuitsignal 5 of the RF antenna circuit 2000 will be presented to the antennacontrol circuit 1200 by means of a first lead of the capacitor device1217, which acts to A.C. couple the internal circuit signal 5 of the RFantenna circuit 2000 to the antenna control circuit 1200.

The second and remaining lead of the capacitor device 1217 passes aportion of the internal circuit signal 5 applied to the first lead ofcircuit component and capacitor device 1217 as a resultant signal on tothe diode device 1216 and the cathode thereof, and the diode device 1215and the anode thereof, and to the resistor device 1214.

When the eventual resonant oscillations from the RF antenna coilapparatus 2002 are present, the diode devices 1215 and 1216 act to clipany excess and undesired voltage peaks from the resultant signalprovided for by means of the second lead of the capacitor device 1217.

In this instance, the resistor device 1214 acts to reference theresultant signal provided for by means of the second lead of thecapacitor device 1217 to circuit ground.

The resultant signal, provided for by means of the second lead of thecapacitor device 1217, is then applied to the input of the inverterdevice 1213, whereby the output of the inverter device 1213 will invertthe resultant signal and pass the inverted resultant signal on to themicrocontroller devices 1100-A by means of signal 9A being presented tothe μC input pin C.

However, if the antenna umbilical cable apparatus 4000 is not attachedto the connector apparatus 1004, or if the RF antenna circuit 2000 isnot attached to the antenna umbilical cable apparatus 4000, then theinternal circuit signal 5, now an open circuit, will still be presentedto the antenna control circuit 1200 by means of a first lead of thecapacitor device 1217, but since no signal of oscillation will bepresent, the capacitor device 1217 becomes, in effect, an open circuitas well.

Therefore, and without the resistor device 1214 being in place, thesecond lead of the capacitor device 1217 and its voltage potential wouldbe considered “floating.” Thusly, in this instance, the resistor device1214 acts to reference the input of the inverter device 1213 to circuitground.

In addition, the diode devices 1215 and 1216 also, in essence, becomeopen circuits.

The effect of having no resultant signal, as would otherwise normally beprovided for by means of the second lead of the capacitor device 1217,is that the input of the inverter device 1213, now referenced to circuitground the resistor device 1214, provides a steady state logical HIsignal as an output to the microcontroller devices 1100-A by means ofsignal 9A being presented the to μC input pin C.

Certain undiscussed circuit signals of FIG. 5 and the RF antenna circuit2000 identified as circuit signal 11 and by the nomenclature “AUDIO,” ascircuit signal 12 and by the nomenclature “SIGDET,” and as circuitsignal 13 and by the nomenclature “GDDATA,” shall now be elaboratedupon.

The origin of these three circuit signals is to be found in FIG. 6,which has yet to be discussed; however, these signals have been somewhataddressed earlier when the RF antenna circuit 2000 was described.

The input circuit signal 11, identified by the nomenclature “AUDIO,” iscaused to be presented to the RF antenna circuit 2000, in part by meansof the connector apparatus 2001 and, ultimately, to a first pin of theaudio device 2003-A. The input circuit signal 11 will be either atcircuit ground potential, providing for “off functionality of thecircuit component and predetermined audio device 2003-A, or applied toone or more waveforms or frequencies, which become audibly notable assound, when presented to the first pin of the audio device 2003-A, thusproviding control for activation of the audio device 2003-A, providingin addition for “on” functionality.

The input circuit signal 12, identified by the nomenclature “SIGDET,” iscaused to be presented to the RF antenna circuit 2000 by means of theconnector apparatus 2001 and, ultimately, to a first pin of the firstLED device 2004. The input circuit signal 12 will be either held at +5Vif SIGDET is active, or applied to the circuit ground potential ifSIGDET is not active to the first pin of the LED 2004 or user feedbackcircuit 2003, thus providing means to toggle the LED 2004 on and off,respectively.

The input circuit signal 13, identified by the nomenclature “GDDATA,” iscaused to be presented to the RF antenna circuit 2000, by means of theconnector apparatus 2001 and, ultimately, to a first pin of the secondLED device 2005. The input circuit signal 13 will be either held at +5Vif GDDATA is active, or applied to the circuit ground potential ifGDDATA is not active, to the first pin of the LED 2005 of user feedbackcircuit 2003, thus providing means to toggle the LED 2005 on and off,respectively.

The remaining undiscussed circuit signals of FIG. 5 and the RF antennacircuit 2000 shall now be addressed.

Circuit signal 4A is presented to the remaining and second predefinedpins of the audio device 2003-A, the first LED device 2004, and thesecond LED device 2005 of item 2003-B, all of user feedback circuit2003, providing for a second circuit ground signal of and to the RFantenna circuit means 2000 by means of the connector apparatus 2001.

Circuit signal 3, applied by means of the connector apparatus 2001, andhaving one or more predetermined frequencies, at a minimum, when active,is presented to a first lead of an RF antenna coil apparatus 2002 as ameans to allow for eventual resonant oscillation of the RF antenna coilapparatus 2002. As the RF antenna coil apparatus 2002 responds to anactively applied input signal 3, a first EM field of flux and carriertransmit EM field of flux signal is created by the RF antenna coilapparatus 2002.

Turning next to FIG. 6, which illustrates a first partial drawing of theanalog front-end 1400, and which is comprised of RF signal and envelopedetector circuit 1400-A and RF signal conditioning circuit 1400-B.

The output signal 2, first illustrated in FIG. 5, and identified by thenomenclature “SIGOUT,” is applied to the anode of the diode 1401, thefirst circuit component and signal rectifier of the RF signal andenvelope detector circuit 1400-A.

The cathode of the diode and item 1401, noted as raw circuit signal 15,is then applied to the anode of the diode 1402, a second circuitcomponent and signal rectifier of the RF signal and envelope detectorcircuit 1400-A, as well as is applied to the capacitor 1407.

The cathode of the diode 1402 is then applied to a resistor device 1403and a capacitor device 1404, whereby a resultant detected signal 16 isboth created and referenced to the circuit ground. The resultantdetected signal 16 remains considerably reduced in amplitude from theapplied output signal 2, and is comprised, in part, of a partiallymodulated carrier transmit signal.

As the RF antenna 2000 is brought within close proximity of the RF tag3000 (or vise versa), the RF antenna coil apparatus 2002 becomesimpressed with the data-modulated return EM field of the flux signalprovided by the RF tag 3000. As this occurs, the data-modulated returnEM field of flux signal provided by the RF tag 3000 appears in part atthe circuit signals 3 and 2 and first lead of the RF antenna coilapparatus 2002 as a backscatter signal.

The resultant detected signal 16 displays a multiplicity of frequencycomponents, comprised at a minimum of the carrier transmit signal of 100kilohertz or greater, as provided by the RF antenna coil apparatus 2002,the data receive signal comprised of 100 kilohertz or greater, andmodulated and provided by the RF tag 3000, as the backscatter, strayEMI/EMF signals, and generally unavoidable internal circuit noise.

Since the resultant detected signal, 16, is of an abbreviated amplitude,and since it is composed of a myriad of frequency components, additionalcircuitry is required so as to extract the desired data signalcomponent, as first provided by the RF tag 3000 from the remainingfrequencies and undesired signal components.

Turning next to the RF signal conditioning circuit 1400-B of the analogfront-end circuit 1400, the resultant detected signal 16 is applied tothe capacitor device 1405 and resistor device 1406, which together act,in part, as a first filter means, and which provide a first variantsignal of the resultant detected signal 16 to the non-inverting input ofthe amplifier device 1429. The resultant detected signal 16 is appliedto a first lead of the capacitor device 1405, whose remaining and secondlead is applied to a first lead of the resistor device 1406, which thecomponents 1405 and 1406 together act, in part, as a first filter means,and which provide a first variant signal, noted as 16A, derived from theresultant detected signal 16 to the inverting input of the operationalamplifier device 1429 and to a first lead of the resistor device 1409,whose remaining and second lead is applied to the output of theoperational amplifier 1429.

The operational amplifier 1429 amplifies the first variant signal 16Aaccording to the value relationship of two resistors 1406 and 1409 andprovides an amplified version of the first variant signal 16A at itsoutput as a first amplified signal, noted as signal 21.

Applied around the non-inverting input and the output of the operationalamplifier 1429, are two NPN transistors, configured as virtual diodelimiter devices 1419, 1420.

The use of the NPN transistors 1419 and 1420 is because the parameter of“distance sensing” is a substantial prerequisite and factor in thedesign of the present disclosure, and as such common diode devices, suchas 1n4148's, could not be incorporated because they exhibit instability,high leakage and conductance, and unsuitable capacitance, even at roomtemperature, especially observable when applied signals to the commondiode devices are approximately +/−70 or so millivolts in amplitude orless.

The present disclosure allows for sensing applied signals less than 70millivolts in amplitude, therefore common diode devices non-ideallyaffect desired signal integrity when amplified. To clarify, thefundamental reason for using NPN transistors 1419 and 1420 is to providefor a more stable signal at the first amplified signal 21 when appliedfirst variant signal is only of a few millivolts in nature. Resultantdetected signal 16 contains only a few millivolts of observablebackscatter and data stream signal component.

The capacitor device 1425 acts to provide enhanced signal integrity andstability and provides frequency compensation about the operationalamplifier 1430.

Resistor device 1439, resistor device 1440, and capacitor device 1441are utilized to obtain a predetermined voltage of 2.5 volts, by meanswherein the resistor devices 1439 and 1440, by virtue of their physicalincorporation and intrinsic values, divide the applied circuit voltageby 2, and whereafter the circuit component and capacitor device 1441acts as a filter and signal stabilizer for the voltage of 2.5 volts,noted as signal 17.

To overcome certain impedance factors associated with the resistordevices 1439, 1440, and the capacitor device 1441, the signal 17 isapplied to the non-inverting inputs of 3 predetermined operationalamplifiers, noted as items 1438, 1437, and 1436, wherein each of whichis configured as voltage followers.

The operational amplifiers 1438, 1437, and 1436, each have at theirrespective outputs, i.e., signals 20, 19, 18, a voltage signal that isalso 2.5 volts, but which the signals are each now of a lo-impedancenature. The signals 20, 19, 18, are then applied to certain otheroperational amplifiers (items 1431, 1430, and the item 1429,respectively) as first circuit voltage reference signals C, B, and A,respectively.

Thus, signal 18 is applied to a first lead of the resistor 1434, thevalue of which was so chosen to approximately equal the parallelresistance value of the resistors 1406 and 1409 so as to reduce offseterrors at the operational amplifier 1429. The remaining and second leadof the resistor 1434, as signal A, a first circuit voltage referencesignal, is then applied to the non-inverting input of the operationalamplifier 1429, completing the desired circuit about the operationalamplifier 1429.

The first amplified signal, 21, outputted from the operational amplifier1429, is then applied to a first lead of the resistor 1410, whoseremaining and second lead is applied to a first lead of the resistor1412, whose remaining and second lead is then applied to the invertinginput of the operational amplifier 1430 and a first lead of the resistor1413, whose remaining and second lead is applied to the output of theoperational amplifier 1430.

However, the resistor 1411 has attached across it a capacitor 1411,which, in synchronicity with the resistors 1410 and 1412, form a secondfilter means.

In addition, the raw input signal 15 provided by both the cathode of thediode 1401 and the anode of the diode 1402 is, as shared above, appliedto a first lead of the capacitor 1407, whose remaining and second leadis then applied to a first lead of the resistor 1408, which together actas a third filter means. The remaining and second lead of the resistor1408 provides for a first alternate signal of the applied output signal2, noted as 15A, to the inverting input of the operational amplifier1430.

The additive combination of the independent signals, as provided by thesecond lead of the resistor 1408, i.e., signal 15A, and the second leadsof paralleled circuit components 1412 and 1411, together, provide for asecond variant signal 21A.

The operational amplifier 1430 then amplifies the second variant signal21A according to the value relationship of the resistors 1410, 1412, and1413, and provides an amplified version of the second variant signal 21Aat its output as a second amplified signal, noted as signal 22.

Applied around the inverting input and the output of the operationalamplifier 1430 are NPN transistors, configured as virtual diode limiters1421 and 1422. Referring back to the transistors 1419 and 1420, and thediscussion thereof, the reason for the use of the NPN transistors 1421and 1422 remains essentially the same as that for using the NPNtransistors 1419 and 1420, and as such, need not be recounted.

Capacitor 1426 acts to provide enhanced signal integrity and stability,and it provides frequency compensation about the operational amplifier1430.

The voltage reference signal 19 is applied to a first lead of theresistor 1435, the value of which was so chosen to approximately equalthe parallel resistance value of the resistors 1410, 1412, and 1413, soas to reduce offset errors at the operational amplifier 1430. Theremaining and second lead of the resistor 1435, receiving signal B, afirst voltage reference signal, is then applied to the non-invertinginput of the operational amplifier 1430, completing the desired circuitabout the operational amplifier 1430.

The second amplified signal 22 outputted from the operational amplifier1430 is then applied to a first lead of the capacitor 1414, whoseremaining and second lead is applied to a first lead of the resistor1415, which the components, 1414 and 1415, together act, in part, as afourth filter and which provide a third variant signal, noted as 22A,derived from the amplified signal 22 to the inverting input of theoperational amplifier 1431, and, a first lead of the resistor 1416,whose remaining and second lead is applied to the output of theoperational amplifier 1431.

The operational amplifier 1431, then amplifies the third variant signal22A according to the value relationship of resistors 1415 and 1416, andpresents an amplified version of the third variant signal 22A at itsoutput as a third amplified signal, noted as signal 25.

Applied around the inverting input and the output of operationalamplifier 1431 are NPN transistors configured as virtual diode limiters1423 and 1424. Referring back to the transistors 1419 and 1420, and thediscussion thereof, the reason for the use of the NPN transistors 1423and 1424 again remains essentially the same as that for using the NPNtransistors 1419 and 1420, and as such, need not be repeated.

The capacitor 1427 acts to provide enhanced signal integrity andstability and provides frequency compensation about the operationalamplifier 1431.

The voltage reference signal 20 is applied to a first lead of theresistor 1433. The value of the resistor 1433 was so chosen toapproximately equal the parallel resistance value of the resistors 1415and 1416 so as to reduce offset errors at the operational amplifier1431. The remaining and second lead of the resistor 1433, as to signalC, a first predetermined circuit voltage reference signal, is thenapplied to the non-inverting input of the operational amplifier 1431,completing the desired circuit about the operational amplifier 1431.

The third amplified signal 25 outputted from the operational amplifier1431 is then applied to a first lead of the resistor 1417, whoseremaining and second lead, providing for a fourth variant signal notedas 25A derived from the amplified signal 25, is applied to the invertinginput of the operational amplifier 1432, and to a first lead of theresistor 1418, whose remaining and second lead is applied to the outputof the operational amplifier 1432.

The operational amplifier 1432 then amplifies the fourth variant signal25A according to the value relationship of the resistors 1417 and 1418,and presents an amplified version of the variant signal 25A at itsoutput as a fourth amplified signal, noted by nomenclature “DATA” and assignal 26, and a subsequent and fifth amplified signal, noted as signal27, a final circuit signal.

The resistor 1442, and resistor 1443 are utilized to obtain apredetermined reference voltage of 2.7 volts, by means wherein theresistors 1442 and 1443, by virtue of their physical incorporation andintrinsic values, divide the applied circuit voltage, and whereafter,the capacitor 1444 acts as a filter and signal stabilizer for thereference voltage of 2.7 volts, noted now as signal 23.

To overcome certain impedance factors associated with the items 1442,and 1443, and the capacitor 1444, the signal 23 is applied to thenon-inverting input of the operational amplifier, noted as item 1445,wherein the item 1445 is configured as a voltage follower apparatus,which provides at its output signal 24, a second voltage referencesignal.

The signal 24 is applied to a first lead of the resistor 1428, the valueof which was so chosen to approximately equal the parallel resistancevalue of the resistors 1417 and 1418 so as to reduce offset errors atthe operational amplifier 1432. The remaining and second lead of theresistor 1432, as signal D, as the second predetermined circuit voltagereference signal, is then applied to the non-inverting input of theoperational amplifier 1432, completing the desired circuit about theoperational amplifier 1432.

The subsequent and fifth amplified signal, noted as final circuit signal27, is ultimately applied to pin D of the microcontroller device 1100-Aof FIG. 2, allowing for receiving the final circuit signal 27 by themicrocontroller device 1100-A.

The fourth amplified signal, noted by nomenclature: “DATA” and as signal26, is ultimately applied to the anode of the diode 1446 of theremaining portion, and second partial drawing of the analog front-end,1400.

Referring to FIG. 7 now, the fourth amplified signal, noted bynomenclature: “DATA” and as signal 26, is applied to the anode of thediode 1446, of the remaining portion of the analog front-end 1400, whichcomprises the RF parameter detection circuit.

The cathode of the diode 1446, a rectifier, is made to couple to a firstlead of the resistor 1447, whose second and remaining lead is thencoupled to a first lead of the resistor 1449 and the capacitor 1448,where together these components provide means allowing for a thirdpredetermined circuit voltage reference signal to be generated, noted assignal 28.

The value of the resistor 1447 is chosen to establish a minimum voltagebase level from which certain predetermined parameters of the finalcircuit signal 26 may ultimately be detected and may be construed to bepredicated on the partial or whole data content of the final circuitsignal 26, wherein the data content is comprised of logically Hi and LOappearing waveforms. The waveforms, when integrated by additional meansof the capacitor 1448, provide a predetermined D.C. voltage level to theinputs and first leads of the resistors 1455 and 1458.

The resistor 1450 has a first lead attached to the applied circuitvoltage, for example, +5V, and has a second and remaining lead attachedto a first lead of a resistor 1451, whereby together, the resistors 1450and 1451 provide means for allowing the creation of a fourthpredetermined circuit voltage reference signal, noted as signal 29,which is then applied to the inverting input of the comparator device1462.

The first lead of the resistor 1455 receiving the third circuit voltagereference signal 28 has attached to its second and remaining lead afirst lead of predetermined circuit component and resistor 1456,providing for a fifth predetermined circuit voltage reference signal,noted as signal 28A, and wherein the remaining and second lead of theresistor 1456 is then applied to the output of the comparator 1462.

The values of the resistors 1455 and 1456 are so chosen as to establishboth a predetermined impedance and a predetermined hysteresis about thecomparator 1462, wherein also, the fifth circuit voltage referencesignal 28A is presented to the non-inverting input of the comparatordevice 1462.

As is well understood by those skilled in the art, a common voltagecomparator device acts to differentiate between two independentlyapplied input signals, i.e., the given signals presented to both theinverting AND non-inverting inputs of the common voltage comparatordevice, whereby the output of which will switch from a logical Hi state,to a logical LO state predicated on the voltage potentials of theapplied input signals.

The comparator 1462 will switch its output logically LO when the fifthcircuit voltage reference signal 28A is less than the fourth circuitvoltage reference signal 29, causing the LED device 1464 to remain dark,thereby indicating no given RF tag device has been detected, andproviding by means of signal 12, noted by nomenclature “SIGDET,” a firstRF parameter detection signal, indication of the same to the RF antennacircuit, 2000, and ultimately, to the RF interrogator 1000.

Contrarily, the comparator 1462 will switch its output logically HI whenthe fifth circuit voltage reference signal 28A is greater than thefourth circuit voltage reference signal 29 by means of the resistor 1457thereby causing illumination of the circuit component and LED device1464, indicating a given RF tag device has been detected, and providing,again by means of the signal 12, “SIGDET,” the first RF parameterdetection signal, indication of the same to the RF antenna circuit 2000,and ultimately to the RF interrogator 1000.

The output of the comparator 1462 additionally provides for a subsequentoutput signal 31, ultimately presented to the input pin E of themicrocontroller 1100-A, allowing for receiving the first RF parameterdetection signal 31 by the microcontroller device 1100-A.

Finally, the resistor 1452 has a first lead attached to the appliedcircuit voltage, for example +5V, and has a second and remaining leadattached to a first lead of the resistor 1453, whose second and thirdremaining leads are then attached to a first lead of the resistor 1454,the junction of which, is connected to the first lead of a capacitor1461, whereby together the items 1452-1454 and 1461 provide means forallowing the creation of a sixth circuit voltage reference signal, notedas signal 30, which is then applied to the inverting input of thecomparator 1463.

The resistor 1453 is variable and provides means for obtaining a 2 to 3volt sixth circuit voltage reference signal, noted as signal 30, and canalso be of a programmable type, controlled by a microcontroller deviceif needed or desired.

The first lead of the resistor 1458 receiving the third circuit voltagereference signal 28 has attached to its second and remaining lead, afirst lead of the resistor 1459, providing for a seventh circuit voltagereference signal, noted as signal 28B, and wherein the remaining andsecond lead of the resistor and item 1459 is then applied to the outputof the comparator 1463.

The values of the resistors 1458 and 1459 are so chosen as to establishboth a predetermined impedance and a predetermined hysteresis about thecomparator 1463, wherein also the seventh circuit voltage referencesignal 28B is presented to the non-inverting input of the comparator1463.

The comparator 1463 will switch its output logically LO when the seventhcircuit voltage reference signal 28B is less than the sixth circuitvoltage reference signal 30, causing the LED device 1465 to remain dark,thereby indicating no valid data stream signal has been detected, andproviding by means of signal 13, noted by nomenclature “GDDATA,” asecond RF parameter detection signal, indication of the same to the RFantenna 2000, and ultimately to the RF interrogator 1000.

Contrarily, the comparator 1463 will switch its output logically Hi whenthe seventh circuit voltage reference signal 28B is greater than thesixth circuit voltage reference signal 30 by means of the resistor 1460,thereby causing illumination of the LED device 1465, indicating a validdata stream signal has been detected, and providing, again by means ofthe signal 13, “GDDATA,” the second RF parameter detection signal,indication of the same to the RF antenna circuit 2000, and ultimately tothe RF interrogator 1000.

The output of the comparator 1463 additionally provides for a subsequentoutput signal 32, ultimately presented to the input pin F of themicrocontroller device 1100-A, allowing for receiving the secondpredetermined RF parameter detection signal 32 by the microcontrollerdevice 1100-A.

Other RF parameter detection signals can be obtained, if desired, suchas the parameter of distance, within limits, and as concerns a given RFtag device to a given RF interrogator or RF antenna device by means ofadditional circuitry and associative circuit signals.

Now that the new and inventive RFID interrogator alignment system,providing for broadened operational functionality and altogether newRFID applications, has been specifically described, it remains thatcertain aspects of the design can or may be alternatively modified fromthe preferred embodiment, and in lieu of the foregoing will be describedin appurtenant detail. However, it is to be understood the followingembodiments are given by way of example only and are not intended tosuggest limits of any nature to the scope and spirit of the presentdisclosure, or as regards application.

As to alternative embodiments, it is assumed the reviewer now has a goodunderstanding of the construction, function, and benefits of anembodiment of the present disclosure. In discussing the followingalternate embodiments then the focus will remain on implementation orapplication of the alternate embodiments.

FIG. 8 depicts an example embodiment and application of the presentdisclosure, 700, wherein a hand-held RF interrogator 100 is illustrated.The merit of items 200, 400, and 500 have already been addressed withregard to items 5000, 6000, and 7000, respectively, and need not beelaborated on here.

However, item 100 of FIG. 8 represents a top-view of a self-contained RFinterrogator system package, wherein it is composed of an RFinterrogator and an RF antenna. As a small enclosed, light weightpackage, it intrinsically offers many benefits both to end-users and asregards applications.

FIG. 9 depicts an example embodiment and application of the presentdisclosure, wherein an application requiring the use of “x,” “y,” and“z” coordinates is illustrated, for example a medical instrumentation orwhere diagnosis or treatment procedures or equipment is concerned.

If item 101, an integrated RF means interrogator, is attached to acomputerized (at some level) medical apparatus, the RF interrogator 101can, at a minimum, provide certain information about the location andcritical alignment of items 301-303, certain RF tags arranged in “x,”“y,” and “z” coordinates by means of items 201-203, remote RF antennameans, also arranged in “x,” “y,” and “z” coordinates, wherein the RFantenna 201 is responsive only to the RF tag 301, and vise versa; andwherein the RF antenna 202 is responsive only to the RF tag 302 and viseversa; and wherein the RF antenna 203 is responsive only to the RF tag303 and vise versa, providing for an enhanced RF transducer alignmentsystem.

Such a system could be attached to, or about, a (perhaps semi-automated)radiation device and apparatus for cancer treatment. Variant embodimentRF tags placed on a given patient's body or about the body could allow,at a minimum, for precise alignment of the radiation device andapparatus so as to eventually execute a reliably placed radiationtreatment.

Additionally, RF antennas 201-203 could be fabricated such that each RFantenna is adjustable along its assigned, dominant axis, providing forinstances wherein the “x,” “y,” and “z” RF tags might be positioned inobtuse ways to each other, and therefore the RF tags might notnecessarily be positioned in a purely spherical or geometric way abouteach other, and in fact may reside at unequal distances from each other.

Additionally still, RF antennas 201-203 could be fabricated such thateach or all the RF antennas are adjustable about a given or expected RFtag detection field (see FIG. 9, upper middle nomenclature and dashedcircle), wherein standard “x,” “y,” and “z” coordinates (purelyhorizontal “x,” and “z,” and purely vertical “y,” might not bepractical), and thus the RF antennas might accommodate beingrepositionable about three-dimensional space.

FIG. 10 depicts an example embodiment and application of the presentdisclosure wherein digital radiography is utilized. Specificallyillustrated is a top-view of a dental digital imaging sensor 600 whereinalso is illustrated a slip-on RF tag 304. The RF tag 304 could be areusable device, and it would slip over the digital imaging sensor 600,a customarily non-reusable device, so that one may obtain exacting x-rayimages by means provided by the RF tag 304 and the present disclosure.

FIG. 11 depicts an example embodiment and application of the presentdisclosure wherein a portable RF interrogator apparatus 703 is shownconstructed, looking similar in nature to a given field-applicable metaldetector device, wherein a handle 701 and a modified remote RF antenna702 labeled “multi-form antenna coil” provides for RF tag detection bymeans of two predeterminedly sized carrier transmit/data receive coils,each possibly operating at differing frequencies, and possibly atdiffering power levels, by means of predetermined RF waveform drivesignals DRIVE 1 and DRIVE 2, and wherein each RF antenna might be ableto be used independently from the other or in synchronicity with eachother.

Item 702-A, the larger of the carrier transmit/data receive coils, mightgenerally provide for broad-field RF tag detection only, wherein item702-B, the smaller of the carrier transmit/data receive coils, mightgenerally provide for near-field RF tag detection as well as criticalalignment RF tag detection.

FIG. 12 depicts an example embodiment and application of the presentdisclosure wherein a multi-RF tag arrangement, via items 803, isutilized with an RF antenna 800 so as to identify an exacting attitudeof an alterable-position flight-surface of an airfoil 804, wherein item810, the alterable-position flight-surface of the top-most figure,depicts a “level flight” position and attitude, and wherein item 810,also the alterable-position flight-surface, but illustrated in thebottom-most figure, depicts a “dive or descend” position and attitude.

An umbilical cable 801 provides certain predetermined signals to andfrom a given flight surface control computer 802, which has the built-incapability to critically identify the position of all flight surfaces ofa given aircraft. Since the RF tags need not protrude from the flightsurfaces, and since they are not prone to wear, contamination, or rust,etc., and need no outside attached power source, they, with an alternateembodiment of the present disclosure, are configured to interface withthe flight surface control computer, 802, provide an ideal platformwhereby a pilot, and/or certain nav-computers, can critically monitorall movable flight surfaces, and potentially, by means of thenav-computers software, provide “safing” measures when “expected” or“normal,” etc. RF tag signals fail to manifest from the RF antennadevices 800.

Referring now to FIG. 13, the RFID alignment system 900 of the presentdisclosure may be applied to a dental x-ray apparatus having an x-rayemitter 912 and extension tube 914. An RF assembly 920 is configured tobe removably or fixedly installed on the extension tube of the x-rayapparatus. The antenna assembly includes a hollow cylindrical portion924 configured to concentrically slide or otherwise attach to the x-rayextension tube. The portion of the antenna that attaches to theextension tube may be configured with an attachment device, such asscrews 928, for fixing the antenna to the x-ray tube. The antennaassembly may further include a flange 922 or may be otherwise configuredto contain an antenna or coil 926. Seating the coil in the holder shouldbe precise and concentric so as to establish proper alignment betweenthe x-ray emitter and the film or sensor. The coil may be glued into theflange or seat of the antenna assembly and a face plate may be providedso that the coil is not exposed to the environment. Channels may beprovided within the assembly to house the wires from the coil to aantenna control assembly 950. An indicator 952, such as a plasticnon-conductive lamp, LED or other device, may be mounted at or near theantenna control assembly 950. The antenna control assembly may beoperably connected to a computer system 960. Such a computer system mayinclude a microprocessor 962 and display device 964. The computer systemmay be used to process the identification from the RF tag and associatedpatient information.

The dental x-ray system further includes an imaging device 930 having aframe 932 for holding the RFID tag, coil antenna and a film (sensor)holder assembly (bitewing) 934. The tag, coil antenna and x-ray film mayalso be contained within a standard dental film holder 936. The filmholder may be manufactured so that it contains an RFID tag with theantenna running around the perimeter of the film. The RF tag may beprogrammed to contain patient information, such as social securitynumber, invoice number, time, date, tooth location, and other dentalrecords. The tag antenna may be configured so that it will not cover thesurface of the film or sensor and may lay coplanar around the film (orsensor) in a circular or rectangular shape, leaving the surface of thefilm or sensor clear for the image. Then tag antenna 932 may be part ofthe film cover 930. The windings that make up the antenna may be castinto the plastic containing the microchip itself. The microchip maycontain a unique number that can be assigned to the patient via thecomputer system. Alternatively, the tag antenna may be placed betweenplastic sheets that are glued to the film or sensor surface. A softwarepackage may be provided for the computer system that communicatesthrough standard serial communication protocols to the leader controlassembly.

In operation, the antenna assembly 920 may be installed on the extensiontube 914 of the x-ray apparatus 910. The film holder assembly 930 isinserted into the patient's mouth and the x-ray operator powers thecontrol system 950. When the antenna assembly 920 and the tag assembly930 are aligned perpendicular and concentric, an indicator light 952shows that the system is aligned and the radiograph is ready to betaken. The antenna will power the tag antenna only when the two areexactly perpendicular and concentric to one another. When this occurs,the indicator light turns on indicating alignment of the two devices(antennas), and at this time the best alignment is achieved.Alternatively, the computer system may be configured such that itinhibits powering of the x-ray emitter until such alignment occurs.

Thus and in conclusion, there has been demonstrated a versatile,inventive, economical, and beneficial RFID interrogator alignmentsystem, providing for broadened operational functionality, andaltogether new RFID applications, independent of any given embodiment.With such a beneficial and suitable design, with manifold applicationswith which to apply the present disclosure, wide use could not onlyresult in a great deal of user-satisfaction and benefit, as well asimproved manufacturers end-product(s), but in some instances, result incertain financial savings for the end-user or others.

While a particular form of the present disclosure has been illustratedand described, it will be apparent to those skilled in the art thatvarious modifications can be made without departing from the inventiveconcept. Accordingly, it will be understood by those skilled in the artthat certain changes in function, form, capacity, size, shape, and/orother detail may be made without departing or detracting from the spiritand scope of the present disclosure. Accordingly, it is not intendedthat the disclosure be limited except by the appended claims.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet, areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary to employ concepts of thevarious patents, applications and publications to provide yet furtherembodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. A radio frequency alignment apparatus, comprising: an interrogatorconfigured to emit at least one interrogation signal within an area ofalignment; at least one transponder configured to emit at least oneradio frequency signal in response to the at least one interrogationsignal from the interrogator; and the interrogator configured to receivethe at least one radio frequency signal from the at least onetransponder and to generate at least one signal that is processed togenerate at least one of a detection signal and an alignment signalregarding the detection of the transponder and the relative orientationof the transponder and the interrogator to each other, respectively. 2.The apparatus of claim 1, further comprising an indicator configured toprovide at least one of a visual and an audio indication of thedetection and alignment.
 3. The apparatus of claim 1 wherein theinterrogator comprises: an analog front end circuit configured toprocess the at least one radio frequency signal from the at least onetransponder and to generate one or more output signals; a microprocessorassociated with the interrogator and configured to process the one ormore output signals from the analog front end circuit; a memoryassociated with the microprocessor for storing data obtained from the atleast one radio frequency signal as processed by the microprocessor; andwherein an indicator is coupled to the microprocessor for indicating atleast the detection of the presence of the at least one transponder bythe interrogator.
 4. The apparatus of claim 1, further comprising animaging device sensitive to x-rays coupled to the at least onetransponder, the imaging device adapted to produce an image when in thepresence of applied x-rays.
 5. The apparatus of claim 4 wherein an x-rayemitter device is associated with the interrogator.
 6. The apparatus ofclaim 1, further comprising an x-ray emitter device associated with theinterrogator and an x-ray imaging device associated with the at leastone transponder.
 7. The apparatus of claim 1, further comprising aplurality of interrogators adapted to communicate with the at least onetransponder.
 8. The apparatus of claim 7, further comprising a pluralityof transponders configured to communicate with the plurality ofinterrogators.
 9. The apparatus of claim 1, further comprising: at leastone amplifier configured to enhance a received at least one radiofrequency signal from the at least one transponder to produce at leastone amplified signal; and at least one filter for conditioning the atleast one amplified signal.
 10. A method for aligning first and seconddevices, comprising: emitting from an interrogator associated with thefirst device an electromagnetic field of flux; emitting a radiofrequency signal from a transponder associated with the second devicewhen the transponder detects the electromagnetic field of flux from theinterrogator; detecting the radio frequency signal from the transponderwhen the first device is in a condition of alignment with the seconddevice; and generating at least one of a detection signal when the radiofrequency signal from the transponder is detected and an alignmentsignal when the first device is in a condition of alignment with thesecond device.
 11. The method of claim 10, comprising moving theinterrogator until the radio frequency signal from the transponder isdetected.
 12. The method of claim 10, comprising moving the transponderuntil the radio frequency signal from the a transponder is detected bythe an interrogator.
 13. The method of claim 10, further comprising:storing patient specific information and procedural and other datawithin the transponder; formatting and serializing of the stored datawithin the transponder to modulate the radio frequency signal emitted bythe transponder; processing the detected radio frequency signal receivedfrom the transponder to obtain the stored patient specific informationand procedural and other data; processing the detected radio frequencysignal from the transponder to obtain condition of alignment informationbetween the first and the second devices; and displaying the patientspecific information and procedural and other data.
 14. The method ofclaim 10, further comprising: placing the transponder associated with anx-ray sensitive imaging device in the mouth of a patient; and moving theinterrogator, which is associated with an x-ray emitter, until the radiofrequency signal from the transponder is detected.
 15. A system forobtaining a dental x-ray, comprising: an x-ray emissions device; aninterrogator associated with the x-ray emissions device and configuredto emit an electromagnetic field of flux; an imaging device sensitive tox-rays; and a transponder associated with the imaging device andconfigured to emit a radio frequency signal when excited by theelectromagnetic field of flux from the interrogator; wherein theinterrogator is configured to detect the radio frequency signal from thetransponder and to generate at least one of a detection signal when theinterrogator detects the radio frequency signal and an alignment signalwhen there is an alignment condition between the an x-ray emissionsdevice and the imaging device sensitive to x-rays.
 16. The system ofclaim 15, further comprising an indicator configured to be activatedwhen the interrogator detects the a radio frequency signal from thetransponder.
 17. The system of claim 15 wherein the x-ray emissionsdevice is configured to inhibit the emission of x-rays until theinterrogator detects the radio frequency signal from the transponder.18. The system of claim 15 wherein the transponder is further configuredto include within the radio frequency signal patient identificationdata.
 19. The system of claim 18 wherein the interrogator comprises: ananalog front end circuit configured to process the radio frequencysignal from the transponder and to generate an output signal; amicroprocessor associated with the interrogator and configured toprocess the output signal from the analog front end circuit; and amemory associated with the microprocessor for storing data obtained fromthe radio frequency signal as processed by the microprocessor; whereinan indicator is coupled to the microprocessor for indicating at leastthe detection of the radio frequency signal from the transponder. 20.The system of claim 19 wherein the microprocessor is configured toactivate the emission of x-rays by the x-ray emissions device when theinterrogator detects a condition of alignment between the interrogatorand the transponder.
 21. The method of claim 10, comprising moving theinterrogator until a desired condition of alignment to the transponderhas been achieved.
 22. The method of claim 10, comprising: moving thetransponder until a desired condition of alignment to the aninterrogator has been achieved.
 23. A system for identifying theattitude of a movable flight surface of an airfoil, comprising: anantenna associated with the airfoil and configured to emit anelectromagnetic field of flux; at least one transponder associated withthe movable surface and configured to emit a radio frequency signal whenexcited by the electromagnetic field of flux; and a computing devicecoupled to the antenna and adapted to generate a signal to the antennato initiate the electromagnetic field of flux and to detect the radiofrequency signal received on the antenna and to generate a movableflight surface position signal in response thereto.
 24. The system ofclaim 23 wherein the computing device is adapted to generate safetysignals when the movable flight surface is not within a normal conditionor radio frequency signals are not received at the computing device. 25.The system of claim 23 wherein the computing device is configured toprovide monitoring of the movable flight surface for a pilot.
 26. Thesystem of claim 23, comprising a plurality of transponders associatedwith the movable flight surface.